620 VDC [RE-wrenches]

[Bob-O Schultze, Electron Connection]

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Drake,
I'd have to agree with Walt that you are up against the Code anyway  
you look at it.
That said, let's look at reality:
We're talking Voc here- no current of any kind flowing.
We're talking Voc at the record lowest temperature recorded.
Clearly, 600V wire does not break down at 601V

Does anyone seriously believe this is -or ever could be in the real  
world- a safety issue?
Not me.
Cheers, bob-O


On Jun 26, 2008, at 12:37 PM, Drake Chamberlin wrote:

>
> Hello Wrenches,
>
> Some inverters are able to withstand voltages above 600 VDC.  The  
> Solectria 95KW can take up to 620 VDC without harming the electronics.
>
> If we size a system so that the record low temperature is gives a  
> voltage of under 620 VDC, a viable system can be installed.  There  
> is a question, however, about the Code compliance of this, since  
> building wire is rated at 600 volts.  Higher voltage wiring is  
> available, but will likely not be cheap or convenient to use.   
> Also, what about 600 V modules and PV cable?
>
> Since this is DC, there are not any cycles to create a voltage  
> peak.  A 600 VAC RMS nominal system can have (if my calculations  
> are correct) a peak voltage of close to 850 volts.  Also, system  
> voltages can range up to 10% from the nominal, resulting in  
> voltages of as high as 660 VAC RMS on 600 volt systems.
>
> The question is, "can we have a system with a possible low- 
> temperature, open circuit voltage of 620 VDC with wiring and  
> modules rated for 600 volts?  Can the other 20 volts be considered  
> within the nominal range?
>
> Thanks,
>
> Drake


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